>>Preconditions:
>>- Thread filter list is filled up
>>- It's set to remove oldest entries when new one is added if list is full
>
>Not sure what I should do here. Can you specify?

You have to duplicate it in order to reproduce the problem below

>
>>Now clicking on the Filter button in a message removes oldest entry from the list but does not add new one.
>
>Thanks, I will take a look at that.